Removing the trapped keys to access the Enclosure Catwalks during observing will cause the GIS to command the telescope into a safe state (i.e. stop everything). This is by design. It prevents inadvertent access to various locations while the telescope and enclosure are in motion.
To gain access, first complete a JHA and discuss this with supervisors and safety personnel.
Failure to follow procedures may result in serious injury or death.
Close M1 Cover (optionally Aperture Cover could be closed).
Stop Enclosure motion (if needed).
Remove trapped keys to gain access (in this case A->B->C).
Personnel safely access catwalk.
Close gate. Return trapped keys C->B->A.
Reset GIS (if needed).
Resume tracking the Sun. (Enclosure: reset, then re-enable drives, begin tracking)
Open the M1 Cover (or Aperture Cover).
Perform tasks as needed.
Close M1 Cover (optionally Aperture Cover could be closed).
Remove trapped keys to gain access (in this case A->B->C).
Personnel safely leave catwalk.
Close gate. Return trapped keys C->B->A.
Reset GIS (if needed).
Resume tracking the Sun. (Enclosure: reset, then re-enable drives, begin tracking)
Open the M1 Cover (or Aperture Cover).